1. Field of the Invention
The present invention relates to a power receiving system which makes improvements especially on a line section between a network transformer and a protector breaker.
2. Description of the Prior Art
In cities, three-dimensional utilization of lands has become active and high-rise buildings have been built actively. In high-rise buildings, the load distribution of power increases in the vertical direction and the load capacity is very large. Because publicly important facilities are accommodated in these buildings, reliability and safety of power service are strongly asked for. The high-rise building is built in a crowded area in cities and therefore the installation area is desired to be as small as possible. For the high-rise building or a plant and equipment in which a large load is concentrated to one location, a network power receiving system having high reliability of power service is considered to be the most suited.
In the network power receiving system in which power from a power source substation is received through a 22 KV or 33 KV distribution line of two to four lines, there are provided on the primary sides of network transformers power receiving breakers alone and on the secondary side a fuse and a protector breaker in association with each network transformer. Protector breakers have their load sides connected in parallel to a network bus, and power is fed to various loads through several trunk lines.
With the above network power receiving system, in the event that a short-circuiting accident occurs on, for example, the primary side or secondary side of the network transformer, an accident circuit is disconnected and power is fed through a sound line to prevent the load from suffering power failure. Therefore this type of system ensures the high reliability of power service which meets customers' needs and recently, has been in high demand.
In the network power receiving system as exemplified in FIG. 2 of U.S. Pat. No. 4,873,601 (teachings of which are incorporated herein by reference), however, in the event that an accident takes place on the secondary side of the network transformer, the network fuse is fused to protect only a network line section between the network fuse and the protector breaker, giving rise to disadvantages that the protective range is narrow, a network fuse dedicated to high voltage must be prepared and the scale of the network power receiving equipment is increased.